a) \(1\frac{1}{3}x = \frac{20}{9}\)
\(\frac{4}{3}x = \frac{20}{9}\)
\(x = \frac{20}{9} : \frac{4}{3}\)
\(x = \frac{20}{9} \cdot \frac{3}{4}\)
\(x = \frac{20 \cdot 3}{9 \cdot 4}\)
\(x = \frac{5 \cdot 1}{3 \cdot 1}\)
\(x = \frac{5}{3} = 1\frac{2}{3}\)
б) \(\frac{21}{5}y = \frac{33}{10}\)
\(y = \frac{33}{10} : \frac{21}{5}\)
\(y = \frac{33}{10} \cdot \frac{5}{21}\)
\(y = \frac{33 \cdot 5}{10 \cdot 21}\)
\(y = \frac{11 \cdot 1}{2 \cdot 7}\)
\(y = \frac{11}{14}\)
в) \(5x = \frac{7}{15}\)
\(x = \frac{7}{15} : 5\)
\(x = \frac{7}{15} \cdot \frac{1}{5}\)
\(x = \frac{7}{75}\)
Ответ: a) \(1\frac{2}{3}\); б) \(\frac{11}{14}\); в) \(\frac{7}{75}\)